The present invention relates generally to agricultural machinery and, more particularly, to a tension adjusting device for chain conveyors in agricultural harvesting machinery.
Agricultural harvesting machines are commonly equipped with chain conveyors to transport crops from one part of the machine to another. In particular, standard combine harvesters are equipped with three chain conveyors. The first chain conveyor, the feed conveyor, transports crops from the cutting table to the threshing mechanism. The second conveyor, sometimes referred to as the tailings or returns conveyor, returns any unthreshed material from the sieve device to the threshing mechanism, while the third conveyor transports the grain to the grain tank. The width of the conveyors determines the number of conveyor chains used. For example, the feed conveyor is normally equipped with two conveyor chains whereas the second and third conveyors are each equipped with only one conveyor chain. The second and third conveyors are also equipped with partition walls which are located centrally between two parallel walls of closed housings surrounding the conveyors. The conveying span of the chain is separated from the empty span by the partition wall.
It is generally known that each chain in a chain conveyor must be pre-tensioned. This pre-tensioning must be regularly checked before starting work and adjusted if necessary. The tension on the conveyor chains must also be relieved when the machine remains unused for long periods of time. For these reasons, each chain conveyor is normally furnished with a mechanical tensioning device. These devices are equipped with pre-tensioned springs in order to absorb overloading on the chain and to prevent the chain from breaking.
A disadvantage of these mechanical tensioning devices is that two people are required to install and operate the system. The tensioning and detensioning of the chains is laborious and time consuming. Moreover, the tensioning device as a whole is relatively expensive. In addition, the tension of each single chain has to be checked during the daily inspection of the harvesting machine prior to starting work.
In accordance with the present invention a tension adjusting device includes a displaceable shaft associated with each chain conveyor. The displaceable shaft may be moved to adjust the tension on the conveyor chain. An adjusting unit contains an adjusting member that is connected with the displaceable shaft by a linkage means. Movement of the adjusting member by the adjusting unit induces movement in the displaceable shaft through the linkage means, thereby adjusting the tension in the conveyor chain.
In one embodiment, the adjusting unit is a hydraulic cylinder, and the piston rod of the cylinder is the adjusting member.
In another embodiment, the linkage means includes a plurality of swing levers supporting the displaceable shaft; a coupling rod is connected to one end of each of the swing levers; and a transverse member connects the ends of the coupling rods opposite their connection with the swing levers with the adjusting member.
In another embodiment, a connector member in the form of a U-shaped yoke is carried by the adjusting member and connects the adjusting member with and rotatably supports the displaceable shaft.
An object of the invention is to propose a simple and particularly installation- and service-friendly arrangement which will permit the tensioning and detensioning processes to be accomplished in the least amount of time.
This and other objects, aspects, features and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the reference drawings.